BIO304H5 Chapter Notes - Chapter 7: Voltage Clamp, Positive Feedback
Document Summary
H&h also used the voltage clamp to observe how holding voltage affects inactivation of the na+current, and hence navchannels: recall that only navchannels showed inactivation in the squid axon. By holding vmthrough a series of voltages, and then stepping to a fixed depolarizing voltage to open navchannels, h&h were able to characterize the navchannel steady state inactivationproperties. So now we understand the voltage properties of navand kvchannel activation, and navchannel inactivation. The % available curve shows us how rmp influences the number of. Navchannels available to us: depolarization from rmp will activate navand kvchannels according to the conducatance curves. Scenario 1: a neuron"s rmp is at -80 mv: 90% of navchannels are available, no channels are activated. If a +30 mv epsp reaches the axon. If a +30 mv epsp reaches the axon: vmreaches -50 mv, some navchannels activate, not enough to overcome the k+leak, the epsp fades as a graded potential.
